try
{
            //Проверяем капчу
            Class.Captcha.ReCaptcha _ReCaptcha = new Class.Captcha.ReCaptcha();
            if (!_ReCaptcha.Check(Request["g-recaptcha-response"]))
            {
                ViewData["Msg"] = _ReCaptcha.sError;
            }
}
catch (Exception ex) { ViewData["Msg"] = ex.Message; return View(); }

        public bool Check(string response)
        {
            if (response == null) { sError = "Нет связи с Google Capcha. Попробуйте позже ..."; return false; }

            //string response = Request["g-recaptcha-response"];
            const string secret = "XXXXXXXXXXXXXXXXXXX";
            var client = new WebClient();
            var reply = client.DownloadString(string.Format("https://www.google.com/recaptcha/api/siteverify?secret={0}&response={1}", secret, response));

            var captchaResponse = JsonConvert.DeserializeObject<CaptchaResponse>(reply);

            //when response is false check for the error message
            //if (!captchaResponse.Success)
            if (!Convert.ToBoolean(captchaResponse.Success))
            {
                if (captchaResponse.ErrorCodes.Count <= 0)
                {
                    sError = "Не извесная ошибка ...";
                    return false;
                }

                var error = captchaResponse.ErrorCodes[0].ToLower();
                switch (error)
                {
                    case ("missing-input-secret"): sError = "Секретный параметр отсутствует ..."; break;
                    case ("invalid-input-secret"): sError = "Секретный параметр недействующий или введён неправильно ..."; break;
                    case ("missing-input-response"): sError = "Вы не ввели капчу."; break;
                    case ("invalid-input-response"): sError = "Вы не ввели капчу."; break;
                    default: sError = "Error occured. Please try again"; break;
                }
                return false;
            }
            else
            {
                return true;
            }
        }

...
catch (Exception ex) { ViewData["Msg"] = ex.Message; return View(); }

dns1.yandex.net
dns2.yandex.net
ns02.parking.ru
ns03.parking.ru